This invention relates in general to vehicle disc brake assemblies and in particular to an improved structure for a disc brake piston heat shield adapted for use in such a vehicle disc brake assembly.
Most vehicles are equipped with a brake system for retarding or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile and light duty truck includes a disc brake assembly for the front wheels of the vehicle, and either a disc brake assembly or a drum brake assembly for the rear wheels of the vehicle. A typical brake system for a medium duty truck includes a disc brake assembly on all four wheels of the vehicle. The brake assemblies are typically actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of the disc brake assembly, as well as the actuators therefor, are well known in the art.
There are two basic types of calipers for use in disc brake assemblies, namely, a "floating" caliper disc brake assembly, and a "fixed" caliper disc brake assembly. A floating caliper type of disc brake assembly is usually used on automobiles and light and medium duty trucks. A conventional floating caliper type of disc brake assembly includes a brake caliper which is supported by a pair of pins for sliding movement relative to an anchor plate which is secured to a fixed, non-rotatable component of the vehicle. A fixed caliper type of disc brake assembly is sometimes used on automobiles and light and medium duty trucks. A conventional fixed caliper type of disc brake assembly includes a brake caliper which is solidly fixed to a fixed, non-rotatable component of the vehicle.
In both types of disc brake assemblies, a pair of brake shoes are supported by the disc brake assembly for sliding movement relative thereto. The brake shoes have respective friction pads which are disposed on opposite sides of a rotor. The rotor, in turn, is connected to the wheel of the vehicle for rotation therewith. To effect braking action, the brake shoes are moved inwardly toward one another so as to frictionally engage the opposed sides of the rotor. Such frictional engagement causes retarding or stopping of the rotational movement of the rotor and, therefore, the wheel of the vehicle in a controlled manner.
To accomplish this in a fixed caliper type of disc brake assembly, the brake caliper assembly includes an inboard caliper assembly disposed adjacent an inboard brake shoe, and an outboard caliper assembly disposed adjacent an outboard brake shoe. One or more hydraulically or pneumatically actuated pistons are provided in respective cylindrical recesses formed in the inboard caliper assembly adjacent the inboard brake shoe, and one or more hydraulically or pneumatically actuated pistons are provided in respective cylindrical recesses formed in the outboard caliper assembly adjacent the outboard brake shoe. This type of construction is commonly referred to as an "opposed" piston caliper design. When the brake pedal is depressed, the pistons urge the brake shoes toward one another and into engagement with the associated side of the rotor. As result, the brake shoes frictionally engage the opposed sides of the rotor.
During frictional engagement of the brake shoes with the rotor, a considerable amount of heat is generated. It is known to provide a heat shield on the piston of the disc brake to block or shield certain components of the disc brake assembly from the heat generated during braking, and/or to prevent fluid boil from occurring as a result of the heat. Thus, it would be desirable to provide an improved structure for a disc brake piston heat shield which protects associated components of the disc brake assembly from the heat generated during braking and minimizes the possibility of fluid boil, yet is relatively inexpensive and easy to manufacture.